Roller Brake Test | Your Guide to Vehicle Braking Assessment

faqs -> braking

A roller brake test is a crucial procedure used to assess the braking performance of heavy goods vehicles (HGVs) and trailers. This test measures braking efficiency, imbalance, and overall system functionality to ensure compliance with safety regulations.

With updated DVSA guidance coming into effect from April 2025, the importance of accurate and reliable brake testing has increased. This article explains how roller brake testing works, why it’s necessary, and how to interpret test results.

For detailed official guidance, refer to the DVSA Guide to Maintaining Roadworthiness.

Contents

• What is a Roller Brake Test?
• How is a Roller Brake Test Performed?
• What Does the Roller Brake Test Measure?
• Current Exemptions and the Transition to Risk Assessments
• Why is Laden Brake Testing Important?
• Understanding Your Roller Brake Test Report
• Final Thoughts

What is a Roller Brake Test?

A roller brake test measures the braking force applied by each axle while the vehicle remains stationary. The test is performed using a roller brake tester (RBT), which simulates road conditions by placing each axle onto rotating rollers that measure braking force as the brakes are applied.

Unlike dynamic brake testing (where a vehicle is tested under real driving conditions), a roller brake test provides a controlled and repeatable method to assess braking efficiency.

How is a Roller Brake Test Performed?

1. Vehicle Preparation:
   • The vehicle is driven onto the roller brake tester.
   • Each axle is tested separately.
   • For trailers, the air supply is connected to a compatible test rig.
   • From April 2025, vehicles must be tested in a laden condition (typically at least 65% of their maximum weight).
2. Axle-by-Axle Testing:
   • Each axle is placed onto the rollers.
   • The rollers rotate the wheels at a controlled speed.
   • The brakes are applied progressively while the system measures braking force.
3. Data Measurement:
   • The brake tester records key performance metrics.
   • Any imbalance, binding, or delay in braking response is detected.
   • Results are displayed on a brake test report, which determines pass/fail status.

What Does the Roller Brake Test Measure?

Braking Efficiency (% of Total Vehicle Weight)

• Service Brake (Foot Brake): Must achieve at least 50% braking efficiency (force vs. vehicle weight).
• Secondary Brake (Emergency Brake): Must achieve at least 25% braking efficiency.
• Parking Brake (Handbrake/Spring Brake): Must achieve at least 16% braking efficiency.

Brake Imbalance (Left vs. Right on the Same Axle)

• A significant imbalance (>30%) can cause vehicle instability and may result in a test failure.

Brake Binding (Residual Brake Force When Released)

• If brakes fail to fully release, they may cause excessive wear, overheating, and poor fuel efficiency.

Current Exemptions and the Transition to a Risk Assessment Approach

Current Exemptions (Before April 2025)

• Unladen tri-axle semi-trailers
• Livestock carriers
• Tankers carrying perishable or hazardous goods

New Requirements from April 2025: Risk Assessments for Exemptions

• Why a laden test is not feasible.
• Alternative monitoring methods.
• Supporting evidence.

Why is Laden Brake Testing Important?

From April 2025, operators must meet one of the following two requirements:

1. Conduct a minimum of four meaningful brake tests per year, including the annual MOT, or
2. Perform one meaningful brake test per year at MOT and supplement it with continuous Electronic Brake Performance Monitoring System (EBPMS) data.

Understanding Your Roller Brake Test Report

The brake test report provides a breakdown of each axle’s performance. The key things to check include:

• Pass/Fail Status
• Braking Forces
• Imbalance Percentage
• Binding Levels

Final Thoughts

Roller brake testing is a critical part of vehicle maintenance and MOT compliance. Ensuring that your HGVs and trailers pass their brake tests can prevent costly failures, improve road safety, and keep your fleet legally compliant.

With the new DVSA requirements from April 2025, it’s essential to prepare for laden brake testing and ensure your vehicles meet efficiency standards. If laden testing is not possible, operators will need to document a formal risk assessment justifying the exemption.